79 research outputs found

    Editorial

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    The publication at hand are the proceedings of the 15th International Conference on Archaeological Prospection held between March 28 and April 1, 2023, in Kiel, Germany. The content of the articles ranges from local to large-scale case studies all over the world and from various archaeological times, over methodological improvements, new processing and visualization techniques to a special session on marine and wetland prospection. Thus, the collection of articles summarizes the state of the art of prospection methods for on- and offshore archaeological investigations

    Geophysical methods for the investigation of soils

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    The aim of the work at hand is the development and enhancement of geophysical processing techniques for pedological mapping. The work is concentrating on (1) the applicability of known and the development of new GPTFs using laboratory measurements under controlled conditions, (2) the areal mapping of the electrical conductivity of topsoil and subsoil using an inversion, (3) the separation of the influences of water and clay content on the electrical conductivity and (4) the development and first application of approaches for pedological mapping with geophysical methods.Das Ziel der vorliegenden Arbeit ist die Entwicklung und Verbesserung geophysikalischer Auswertemethoden zur flÀchenhaften bodenkundlichen Kartierung. Dabei konzentriert sich die Arbeit auf (1) die Anwendbarkeit von bekannten und die Entwicklung von neuen GPTFs anhand von Labormessungen unter kontrollierten Bedingungen, (2) die flÀchenhafte Kartierung der elektrischen LeitfÀhigkeit von Ober- und Unterboden mit Hilfe einer Inversion, (3) die flÀchenhafte Trennung von Wassergehalts- und Tongehaltseinfluss auf die elektrische LeitfÀhigkeit und (4) die Entwicklung und erste Anwendung von AnsÀtzen zur bodenkundlichen Kartierung mit Hilfe geophysikalischer Methoden

    Seismic evidence of a link between subducted oceanic faults and volcanism: A case study from South Central Chile

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    The south-central Chilean subduction zone was investigated at 39-40°S by a passive seismic experiment. The investigation area comprises the maximum slip of the great 1960 Mw 9.5 Valdivia earthquake. The incoming Nazca plate is permeated by a number of major fault zones including the Valdivia fault zone and the Mocha fault zone which seem to have behaved as a barriers for the rupture propagation of large earthquakes in the past. The investigated sector is also home to the Villarrica volcano - one of South America’s most active volcanoes. In the extension of the Valdiva fault zone we observed a cluster of increased seismicity in the subducting plate at depths between 80 km and 120 km, where dehydration of the subducting plate occurs. The focal plane solutions of this cluster show predominantly strike-slip motion. Tomographic images show decreased P- and S-velocity and increased ratio between the seismic cluster and the volcanic center of Villarrica, QuetrupillĂĄn and Lanin, corresponding to an increased content of ïŹ‚uids or melt. Additional geochemical investigations show that the magma of Villarrica volcano has an enhanced ïŹ‚uid signal compared to the other volcanoes of the Southern Volcanic Zone of Chile. It can be assumed that the Valdivia fault zone serves as the source for the ïŹ‚uids. Before the plate subducts, water can penetrate the plate through faults within the Valdivia fault zone. Serpentinization would build the water into minerals. Inside the subduction zone the Valdiva fault zone is reactivated by dehydration reactions at a depth of about 100 km. The released ïŹ‚uids rise towards the volcanic center causing the tomographic anomalies. At the end this leads to an increased degree of melting and a higher activity of Villarrica volcano

    Physical Parameters and Contrasts of Wooden Objects in Lacustrine Environment: Ground Penetrating Radar and Geoelectrics

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    We investigate how suitable ground penetrating radar (GPR) and geoelectrics are to prospect the remains of submerged wooden archaeological constructions in the water column. For this purpose, we determined the contrasts of electric resistivity and dielectric permittivity from measurements on present-day wood samples, serving as simpliïŹed approximations of water saturated and undegraded archaeological wood. As common substitutes of hard and soft construction wood, we investigated oak and spruce wood. The electric resistivity and dielectric permittivity were determined with increasing moisture content from small-scale electric and GPR measurements using a Wenner alpha array and a 2 GHz Palm antenna in a watering experiment. In a water-saturated state, resistivity values of 20 were observed. The anisotropy eïŹ€ects and deviations of the wood species were seen to be up to 30%. On the basis of this, the relative material contrasts of wood with respect to fresh water, sand, and clay were calculatedand compared to values found in the literature for seismic contrasts. Geoelectric, GPR, and seismic measurements show contrasts of 0.3 to 0.8, −0.4 to 0.2, and −0.24 to 0.35, depending on the surrounding material and structural orientation of the wood. The highest contrasts were found for wood in fresh water, followed by clayey and sandy subsoils. On the basis of the determined contrasts, analytical calculations were performed showing that an object of 0.5 m diameter can be detected at depths between 0.5 m and 1.5 m with geoelectrics (Schlumberger) and at depths between 0.5 m and 3 m with ground penetrating radar measurements (400 MHz)

    Latest Pleistocene and Holocene Floodplain Evolution in Central Europe—Insights from the Upper Unstrut Catchment (NW-Thuringia/Germany)

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    The upper Unstrut River is located in Germany at the modern Central European climate boundary of Cfb and Dfb climate. The river drains a loess landscape, which has experienced important environmental changes throughout the last 12,000 years. To evaluate the impacts of these changes on floodplain evolution, a multi-proxy research program, consisting of 2D electrical resistivity tomography profiling (ERT), vibracoring, and sedimentological investigations, 14C and OSL dating were applied. From base to top the investigations the following fluvial deposits were revealed: (1) gravels embedded in a fine-grained sediment matrix (interpreted as fluvial bedload deposits); (2) silty sediment with pedogenic features (interpreted as overbank floodplain deposits); (3) peat and tufa deposits (interpreted as wetland deposits) intercalated by pedogenetically influenced silty sediments (interpreted as overbank deposits); (4) humic silty sediment with some pedogenic features (interpreted as overbank floodplain deposits); and (5) silty sediments (interpreted as overbank deposits). Radiocarbon and luminescence dates yielded the following periods for sediment formation: (1) Younger Dryas to Preboreal period (around 11.6 cal ka BP); (2) Preboreal to early Atlantic period (approx. 11.6 to 7.0 cal ka BP); (3) early Atlantic to late Subboreal period (approx. 7.3 to 3.4 cal ka BP); (4) late Subboreal to early Subatlantic period (2.9 to 2.3 cal ka BP); and (5) late Subatlantic period (approx. 1.0 to 0.6 cal ka BP). The results suggest that floodplain development during the latest Pleistocene and early Holocene (approx. 11.6 to 7.0 cal ka BP) was considerably controlled by climatic conditions and short-term climate variabilities, which caused gravel deposition and overbank sedimentation. Afterwards floodplain conditions varied between rather stable (peat and tufa development, initial soil formation) and active periods (deposition of overbank fines)

    Hunte 1 reloaded – combining ground penetrating radar, electrical resistivity tomography, corings and excavations at the Neolithic domestic site Hunte 1, Germany

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    With the help of geophysics an old excavation plan from the 1930ies and 1940ies could be relocalized. The interface between peat and sand can be traced over the whole area by GPR. Diffraction hyperbola in GPR data as well as excavation revealed piles and timbers. The Neolithic domestic site was much larger in extent and more complex than known before our research

    The Applicability of an Inverse Schlumberger Array for Near-Surface Targets in Shallow Water Environments

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    We investigate the applicability of offshore geoelectrical profiling in the littoral zone, e.g., for archaeological prospection, sediment classification and investigations on coastal ground water upwelling. We performed field measurements with a 20 m long multi-electrode streamer in inverse Schlumberger configuration, which we used to statistically evaluate measurement uncertainty and the reproducibility of offshore electric resistivity tomography. We compared floating and submerged electrodes, as well as stationary and towed measurements. We found out that apparent resistivity values can be determined with an accuracy of 1% to 5% (1σ) depending on the measurement setup under field conditions. Based on these values and focusing on typical meter-scale targets, we used synthetic resistivity models to theoretically investigate the tomographic resolution and depth penetration achievable near-beach underneath a column of brackish water of about 1 m depth. From the analysis, we conclude that offshore geoelectric sounding allows the mapping of archaeological stone settings. The material differentiation of low-porosity rock masses 2 m if floating electrodes are used

    Hyperbola detection with Retinanet: application to new sites and scalability

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    The application of Retinanet to new datasets detected about half of the hyperbola present. Combining the detections from images with different aspect ratios results in better performance. The aspect ratio of the images is a crucial factor for detection

    Investigating remains of an early modern manor in Noer (Schleswig-Holstein) using 3D ERT and GPR – first results

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    Buried remains of an early modern manor are investigated using ERT and GPR. For this purpose, 3D approaches are applied for high-resolution imaging. The results of both methods are interpreted in combination with archaeological findings

    Seismic full waveform inversion in archaeological prospecting

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    Seismic full waveform inversion is introduced as novel high-resolution imaging tool in archaeological prospection. The full waveform inversion approach allows the high-resolution characterization of low-contrast sedimentary layers, high-contrast stone wall structures and air-filled cavities
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